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A229754 Number of defective 4-colorings of an n X 7 0..3 array connected horizontally, vertically, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..3 order. 1
210, 20032, 41872, 69198, 113330, 186396, 314700, 557578, 1046550, 2070144, 4258696, 8984046, 19221426, 41402836, 89392212, 192991026, 416096878, 895389192, 1922585088, 4119014998, 8805491466, 18784661532, 39993300364 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 9*a(n-1) - 33*a(n-2) + 63*a(n-3) - 66*a(n-4) + 36*a(n-5) - 8*a(n-6) for n>11.

Empirical g.f.: 2*x*(105 + 9071*x - 65743*x^2 + 170088*x^3 - 187916*x^4 + 63288*x^5 + 30816*x^6 - 21756*x^7 - 2936*x^8 + 504*x^9 + 1360*x^10) / ((1 - x)^3*(1 - 2*x)^3). - Colin Barker, Sep 21 2018

EXAMPLE

Some solutions for n=3:

..0..1..0..0..2..0..1....0..1..0..2..3..0..1....0..1..0..2..3..2..1

..2..3..2..3..1..3..2....2..3..3..1..1..2..3....3..2..3..1..0..1..3

..1..0..2..0..2..0..1....0..1..2..0..3..0..1....0..1..0..2..3..2..1

CROSSREFS

Column 7 of A229755.

Sequence in context: A140904 A092711 A187308 * A089514 A289328 A014979

Adjacent sequences:  A229751 A229752 A229753 * A229755 A229756 A229757

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 28 2013

STATUS

approved

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Last modified December 17 09:23 EST 2018. Contains 318193 sequences. (Running on oeis4.)